This invention relates to a flexible calibrator which is used to measure the diameter of the lumen in a stenotic segment of blood vessel when the vessel proximal to the stenosis is highly tortuous. At its distal end the calibrator is provided with a bulb-shaped or oval member which is used as a gauge member to determine the lumen size of the vessel.
The prior art known to me consists of the presently used calibrator instruments. They are provided with lumen-sizing ovals but are rigidly constructed. Their rigidity prevents them from being advanced through sharply winding segments of a vessel in order to reach and measure the desired area of stenosis.